The present invention relates to in-mold labeling devices and in particular to in-mold label transferring devices for blow molding machines which include a pair of mold carrying platens which move between various stations within the machine.
Blow molding machines of various designs are used to blow mold hollow objects such as bottles or the like. One typical machine utilizes a pair of movable platens which each carry a mating mold section. These platens are movable to converge and separate the mold sections, and also move in unison from one operation station within the machine to another so that various steps in the blow molding process may take place simultaneously on different sets of platens.
Machines of the type mentioned above normally utilize some type of extrusion device or similar process to produce a molding material parison. While the mold is open and the platens separated, the platens are shifted in order to position the mold around the parison. The platens are converged to close the mold and are then moved to a calibration station where the bottle is blown.
With such blow molding machines, it is beneficial to apply container labels to the bottles during the blowing process. A preprinted plastic label, more particularly, can be thermoplastically bonded to the bottle during the blowing process, obviating the otherwise necessary step of applying a label during a subsequent operation. Such preprinted plastic labels applied during the molding process are much more resistant to abrasion, can be more readily aligned and, in general, make for a more attractive product package than can be achieved by utilizing a post-blowing labeling operation. Various methods have been used to place labels within molds to take advantage of these improved results. For example, a variety of label placing arms have extended from the machine frame to place the label within the open mold. Other methods insert the label through a separate opening and into the mold or apply a labeling ink to the mold surface.
Various difficulties are experienced with the methods set forth above. The platens and molds must be precisely registered with the label applying apparatus in order for the label to be placed properly on the mold and thus on the blown object. This alignment is often difficult to achieve with such moving platens, since platen and mold open time is desired to be kept at a minimum. For this reason, the label transferring operation must be performed very rapidly. Additionally, some labelingg devices require that the platens remain stationary throughout the label placement procedure. The platens may not move from one station to another during the label transferring process, which increases the amount of time required for each cycle of the blow molding machine and therefore reduces the machine's production capacity.